Sigma 50B power supply issues

[Flappa]

Hello forum friends. I have a Sigma 50B slot machine. I think I have the common issue of the power supply going bad. When I got it a few months ago, I noticed issues with the 5 V system (I think) but was able to limp along until now. The only thing that turns on is the fluorescent lights and from what I have read they don't use the power supply at all. With machine turned on, I used a multimeter, set to VAC,  and then AC, and back probed, with positive probe, the wires in the Molex that attaches to the PS board, and negative probe touching clean metal In cabinet. I assume that's how to check power from power supply, but not sure. (See first pic) All were 0's, so I tested MM on another machine and it read proper voltage. All capacitors look fine, battery is 2.69 V, and I could not find any fuse. I'm wanting to know if I have done things right and if there's anything else I should do to confirm power supply being shot. Also wanting to know which route to go for a new Power Supply. TIA

[Flappa]

Pics

[Flappa]

Pics

[Chris-socal]

Ground is the black wires on that connector.
You need to check all 3 rails (5v red, 12v yellow,  24v orange). Using black wire as ground. All 3 black wires are connected on the bottom of the board.

[Flappa]

Thanks Chris. I back probed the wires in that connector again for power using the black wires as ground and still got zero on the red, yellow, and orange wires.

[Chris-socal]

Very common problem. I suspect the fuse blew as a result of the failure. Its pretty easy to pull the entire PS. Just loosen the 4 nuts (don’t remove them), slide the entire frame up and over the nuts.

I saw them on ebay for around $50, you need to be sure you are getting one that has the 3 power rails you need. They are typically listed as Artesyn.

You can always try replacing the capacitors but many times other components have shorted out and the project snowballs. You can also reach out to one of our supporting shops, they might stock them.
Midwest Slots or K-Lar

Chris

[Flappa]

My novice eyes do not see any issues on the PS and the fuse is not blown. Can that be normal? Should I do any other tests to confirm the PS is bad before I order a new one. Is there a part number on it anywhere that I could find to make sure I order the same/ Compatible.one.

[Chris-socal]

Did you verify you are getting AC into the PS? It would be the black and white wires going to the PS on a separate connector with the ground wire.
Sometimes if the caps are out of tolerance the PS will go into shutdown. Some of those rectifiers mounted to the heat sink can blow out. They are tough to test in circuit because there is a coil across them and it always looks like a dead short to the meter.



Chris

[Flappa]

Just tested the black & white power wires in the connector for the PS and it showed about 120. So it seems like it was getting power. With the history of these PS's, I totally suspect the PS is bad. I've just heard about the capacitors expanding or leaking and the fuse being blown when the PS doesn't work anymore, but I don't see any of that on mine. I sent a PM to Jim to see if he has any.

[Chris-socal]

Nope, the 2200ufs probably won’t bulge.
I’m not saying that’s the problem for sure but it’s a possibility.
I have one I cannot fix, I tried everything.
Try diode checking the IRF840, it’s the single component mounted to the heat sink behind the transformer.
It should check as a diode from the middle pin to each outside pin. If you don’t have a diode setting on your meter just use ohms measurement , it shouldn’t be dead shorted.

[Flappa]

With meter set to resistance/2000 I tested that diode and both legs came out to 045. I have no problem buying a new power supply if it is around $50. I really suspect it is bad, I just wanted someone that knows more than me to know that I can't visually see anything wrong with it, and if that could be normal.

[Chris-socal]

Well, the entire output side isn’t shorted so it’s either one of the outputs is causing a shut down or something else is causing shutdown.
The only thing Im not sure about is if the third tail is 24v or -12. Ma machines are 24v.

Chris

[Flappa]

If I call Jameco to see if they have a compatible meanwell PS for my Sigma, can you tell me
what Info about my PS are they going to need from me?

[Flappa]

I got a Mean Well power supply (manufacturer part number RQ - 125D) from Jameco for about 50 bucks, and all is up and running perfectly. I wanted to make sure I posted the fix for my problem because I've read through too many threads where the original poster does not post what the solution to the problem was. That's frustrating, although you do learn some troubleshooting for the issue, you never find out how It was solved.

[Chris-socal]

That’s fantastic news! So many times the power supplies are the issue on these machines. Sometimes you can even get a meter reading but they don’t provide sufficient current.
Congratulations!

Chris

[Flappa]

Update on my Sigma 50B, now powered by the mean well ps. There are 2 things going on with it that I could use assistance with. First, the machine is playable, but at random times, after the spin is done the display, button lights, and reel power goes out. Most of the time, they all come back on about 3 or 4 seconds later, and I can play again for anywhere between 1 and 40 plays until it happens again. One time when it happened, it kept going out as it tried to power back up, then I turned the machine off and back on and that stopped happening. The second thing I would like help to understand is when I measure the volts on the 5V and 12V output on the ps they read good, but on the 24V, it reads 1.

[Chris-socal]

We need someone who is literate on switching power supplies.
To me, this sounds like a power supply that is cutting out due to excessive load.
The original PS from my machine appears to be rated at 160 total watts.
The Meanwell you purchased is rated at 124 total watts.
I once read that people were replacing the original unit with a unit that was even higher rated than the original.
The hard part about finding substitute equipment is knowing with confidence that what you are buying is truly equivalent.
Each power rail might be rated similar to your original unit but the entirety if all the rails has a limit. I think.
User 61Wally is very literate in switching power supplies but I think he is unavailable until next week. I will reach out to him.
The stepper motors are efficient but I think they are capable of drawing some power. I assume it never goes into this shut down when idle? When you say the display goes out, what exactly do you mean? Are you talking about the LED readouts?


Verify that you have really solid ground contacts. They used 3 taps on the original.

Double check that you are not using the -12v rail by accident. Your machine does not use it.

Chris

[Flappa]

It does not happen when the game is on and at idle. It only happens sometimes after reels finish their spin. What I mean by display going out is the numbers in the winner paid, credits, and coin in window all go blank.
The original power supply was a NFS80 -,7602c and had 80 watts. The new one, like you said, has 124 watts. I did check to make sure all my wire connections to the new power supply were good and tight and they were. The 5V,12V, and 24V connector actually has 4 black ground wires. I assume I did it right, but it seemed odd and a bit tricky to get all four ground wire fork terminals on the one ground connection of the ps. See pics

[Flappa]

Pics

[Flappa]

I should also mention how random this issue happens. Listed below are a handful of plays/bets and when the power cut out. I shut the machine off for 15 seconds in between each session.

- 300 plays no problems
- Issue happened 3 times in 9 plays
- 100 plays no problem
- 100 plays no problem
- Issue happened on 57th play and kept cutting out when it tried to come back on, so had to shut it off.
- Issue happened on 4th and 6th play and then couldn't stay powered on so had to shut machine off again.
- 200 plays with no problem.